Breeding Albino BN's with Longfin Normal BN's?

[Patr1ck]

If I bred an albino regular fin bristlenose with a brown long fin bristlenose would I have any longfin albino fry?

Thanks,
Pat

[MatsP]

No, most likely you will get all brown short fin ones. If you start crossing those fry, you can probably breed in both variants.

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Mats

[Suckermouth]

Probably not.

What I'm about to say is based on the Mendelian inheritance. There's more info on Wikipedia, although I'm going to try to be clear while also not writing too much text to read.

Albinism and long fins are both recessive alleles. That is, these alleles will be masked by any dominant alleles, such as the normal wild-type traits (brown and short fins). What this means is that a fish needs to inherit recessive alleles from both parents to express it so that there are no dominant alleles. If a fish inherits a recessive allele and a dominant allele, the recessive allele is masked. The only way you can guarantee your fry to inherit long fins and albinism from both parents is if both parents are albino and longfin; this guarantees that the fry will only inherit the recessive alleles.

However, your fish are not this.

What Mats describes is the most likely possibility. That is, the albino fish is pure ("homozygous" = having two alleles that are the same) for the short fin trait and the longfinned fish is pure for the brown trait. This will result in absolutely no young being albino and longfinned. This is because the albino fish's short fin alleles are guaranteed to be inherited by its young because it can only contribute dominant short fin alleles, which will mask the recessive long fin allele expression. Albinism will be masked from the brown allele inherited from the long-finned fish.

However, it might be possible that while one of the parents is pure/homozygous for the dominant trait they have, either of the parents might also have one recessive allele for one of the traits, but it is hidden because it is recessive. There are two possibilities here.

The albino parent could have a recessive allele for the long-finned trait ("heterozygous" = having two different alleles); because the allele is recessive, it would be hidden by a dominant short-finned trait. Again, we are assuming the brown fish is pure for the brown allele. If this is the case, you will have 50% brown, long-finned fry and 50% normal fry.

The second possibility is the long-finned parent could have a recessive allele for the albinism trait. Here we are assuming the albino fish is pure for short fins. If this is the case, you will have 50% albino, short-finned fry and 50% normal fry.

It is also possible that both parents are heterozygous (= the albino fish has a hidden long-finned allele AND the long-finned fish has a hidden albino allele). In this case, you will have 25% normal fry, 25% albino/shortfin fry, 25% brown/longfin fry, and 25% albino/longfin fry.

In all of these situations, the fry will inherit the recessive alleles from their parents, so the fish that do not express albinism or long fins can still pass these on to their own fry, which is what Mats alluded to.

Because recessive alleles are hidden, it is impossible to know what alleles your fish have with certainty, but I've given all the possibilities. If you breed them, we can find out exactly what alleles the parents have based on the ratios of fry I gave above.

[Patr1ck]

Wow! Thanks for all the info guys.

Pat

[Bwhiskered]

I have found that the females carry the gene for finnage. I crossed a male short finned albino that was pure from short fin stock that had been around before long fins were developed. He spawned with a brown lace long fin female. All the resulting fry were brown but about 20% were long fin. They have grown into the largest and most beautiful fish that now produce both albino and brown fry in long and short fin.[img]

My prize male

Very long fins

[/img]

[MatsP]

I have found that the females carry the gene for finnage. I crossed a male short finned albino that was pure from short fin stock that had been around before long fins were developed.

How do you know that the male was pure short-fin stock? Have you tried crossing the male's offspring with their siblings, to see if those give off long-fins.

As far as I know, long fin variety of this fish has been around for quite some time, and it's almost certain that long-fin genetics are present in a small proportion of all wild-caught fish - it's just not very common. [I base this on the fact that so many very different varieties of fish are able to give long-fin varieties when bred in captivity - I could probably come up with half a dozen species, of the top of my head, from as many different parts of the fish-family tree].

By the way, I have a brown female that when bred with her own offspring (by accident) throws albino. I don't hold that as evidence of the female being the carrier of the albino genes...

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Mats

[Bwhiskered]

I have found that the females carry the gene for finnage. I crossed a male short finned albino that was pure from short fin stock that had been around before long fins were developed.

How do you know that the male was pure short-fin stock? Have you tried crossing the male's offspring with their siblings, to see if those give off long-fins.

As far as I know, long fin variety of this fish has been around for quite some time, and it's almost certain that long-fin genetics are present in a small proportion of all wild-caught fish - it's just not very common. [I base this on the fact that so many very different varieties of fish are able to give long-fin varieties when bred in captivity - I could probably come up with half a dozen species, of the top of my head, from as many different parts of the fish-family tree].

By the way, I have a brown female that when bred with her own offspring (by accident) throws albino. I don't hold that as evidence of the female being the carrier of the albino genes...

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Mats

My male came from the first stock of albinos that came to North America. That was years before the long fins were developed and all the bushynose crossed up as they are today. I have been breeding all types of fish for over 55 years.

[Suckermouth]

I have found that the females carry the gene for finnage. I crossed a male short finned albino that was pure from short fin stock that had been around before long fins were developed. He spawned with a brown lace long fin female. All the resulting fry were brown but about 20% were long fin. They have grown into the largest and most beautiful fish that now produce both albino and brown fry in long and short fin.

If long fins are sex-linked (which I'm assuming is what you mean?) then all of your long-finned fry from that cross should be the same gender (presumably they are all male). If not, then it is not sex-linked.

I looked it up, and long fins in zebra danios are dominant (and AFAIK not sex-linked). This is likely the case in Ancistrus too, which changes what I said in my previous post.

First of all, this means that short-finned must be pure. That means that an albino short-finned fish is pure at both alleles. The only possible things that change things up are hidden alleles in the long-finned brown fish. There are four scenarios:

1. Albino short-finned (bbll) x pure long-finned pure brown (BBLL) = 100% long-finned brown fry (BbLl)
2. Albino short-finned (bbll) x pure long-finned heterozygous brown (BbLL) = 50% long-finned brown (BbLl), 50% long-finned albino (bbLl) fry
3. Albino short-finned (bbll) x heterozygous long-finned pure brown (BBLl) = 50% long-finned brown (BbLl), 50% short-finned brown (Bbll) fry
4. Albino short-finned (bbll) x heterozygous long-finned heterozygous brown (BbLl) = 25% long-finned brown (BbLl), 25% short-finned brown (Bbll), 25% long-finned albino (bbLl), 25% short-finned albino (bbll).

In parentheses are genotypes... It just made it easier for me to think it through. B stands for brown, L stands for long fins; lowercase are the recessive alleles albinism (b) and l (short fins). Clearly, none of these ratios are what Bwhiskered had. The 3rd scenario has the types of fish that Bwhiskered got, but not in the correct proportions.

It should be noted that the long-finned fry of scenario 3 is heterozygous for both genes. What this means is that if you cross them, you get a 9:3:3:1 ratio of all four different types: ~56% brown longfin, ~18% albino longfin, ~18% brown shortfin, and ~6% albino shortfin.

So, how do we explain Bwhiskered's odd ratio? Sex-linkage would still yield 50% or 100% long-finned fry from the albino x long-finned brown female cross, so that is not a satisfactory answer. There are a few possible explanations I can think of, but none which I am confident in.

1. Prefertilization differences: For example, sperm that carry the long-finned gene may not fertilize eggs as often that carry the short-finned gene, which would result in fewer long-finned fish. This specific example does not explain Bwhiskered's ratio as female had the long fins, not the male. Perhaps more eggs are produced that hold short-finned alleles for whatever reason, or that eggs that hold long-finned alleles also are harder to fertilize. Who knows? I don't.

2. Postfertilization differences: For example, perhaps long-finned embryos do not develop full term as well as short-finned embryos, or other such things. Assuming inviability (postfertilization mortality), to get to Bwhiskered's ratio of 20% long-finned fry from scenario 3 (all brown fry with 50% long-finned fry/50% short-finned fry), 75% of the long-finned fry (37.5% of the total fry) would have to inviable. I find this unlikely as long-finned fish are fairly common, and long-finned fish tend to be healthy AFAIK.

3. If Bwhiskered's fish were not kept in pairs, but were kept with other short-finned female bristlenoses, there is also the possibility that Bwhiskered's male was brooding fry from short-finned as well as long-finned females. This would easily explain the difference in the ratio, but seeing as Bwhiskered is a breeder he probably had the fish separated.